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Problem with Composite-id

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orribl

Post subject: Problem with Composite-id

Posted: Tue Aug 07, 2007 5:21 am

Newbie

Joined: Thu Jun 14, 2007 8:10 am
Posts: 7

Hi,
I have a problem with two tables with composite-ids.

First Table:

FirstTablePK(PK)

Second Table:

FirstTablePK(FK)(PK)

SecondTablePK(PK)

I know it's a bad design, but it's used in production and I can't change it.

Now I tried to map that with annotations to classes. The first class is working fine, but I don't know how to map the second class. I used the Embedded-Annotaion, but it doesn't work properly.

Here are my classes

Code:

@Entity
@Table(name="FirstTable")
public class FirstClass implements Serializable{
   @Id
   @Column(name="FirstTablePK")
   @Type(type="integer")
   private Integer id;

   @Column(name="Name")
   @Type(type="string")
   private String name;
}

Code:

@Entity
@Table(name="SecondTable)
public class SecondClass implements Serializable{
   @Id
   private SecondTablePK id;

   @Column(name="Name")
   @Type(type="string")
   private String name;

   @Embeddable
   public class FilialePK implements Serializable{
      private Integer id;
      private FirstClass firstClassImpl.
   }
}

Now I don't know how to make this working. I searched for some examples in the web but didn't found much...
Does anybody know how to solve this....?

Thanks in advance

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thatmikewilliams

Post subject:

Posted: Tue Aug 07, 2007 6:37 am

Expert

Joined: Fri Jul 13, 2007 8:18 am
Posts: 370
Location: london

If you're getting an error something like "could not determine type..." try specifying the relationship to FirstClass in SecondClassPK:

Code:

public class FilialePK implements Serializable{ 
      private Integer id; 
      @ManyToOne   // <-------- HERE
      private FirstClass firstClassImpl. 
   } 

If you're having other problems you need to post the details.

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orribl

Post subject:

Posted: Tue Aug 07, 2007 6:47 am

Newbie

Joined: Thu Jun 14, 2007 8:10 am
Posts: 7

Hi thatmikewilliams,

thanks for your post.

Don't I have to tell hibernate which columns in the table to take. Where from does hibernate know that the SecondTablePK in the SecondTable is the id-Attribute of the PK-Class.

What kind of details do you mean?

Thanks

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orribl

Post subject:

Posted: Tue Aug 07, 2007 6:48 am

Newbie

Joined: Thu Jun 14, 2007 8:10 am
Posts: 7

I made a mistake in the first post, of course it has to be SecondTablePK and not FilialePK at the class declaration...

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thatmikewilliams

Post subject:

Posted: Tue Aug 07, 2007 7:20 am

Expert

Joined: Fri Jul 13, 2007 8:18 am
Posts: 370
Location: london

You can specify the column name with @JoinColumn

e.g.

Code:

public class FilialePK implements Serializable{ 
      private Integer id; 
      @ManyToOne 
      @JoinColumn(name = "FirstTablePK")
      private FirstClass firstClassImpl. 
   } 

Quote:

Where from does hibernate know that the SecondTablePK in the SecondTable is the id-Attribute of the PK-Class

I'm not sure I understand what you mean. You've defined a composite PK in the second table. The id attribute of the SecondTablePk class is just one part of the second table's PK.

Quote:

What kind of details do you mean?

Error messages, stack traces, sql, etc. See:
http://www.hibernate.org/ForumMailingli ... AskForHelp

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